Well packer



Jan. 18, 1966 T. J. CARTER 3,229,767

WELL PACKER Filed Dec. 51, 1962 5 Sheets-Sheet 1 INVENTOR.

Ma /W T- J- CARTER WELL PACKER Jan. 18, 1966 5 Sheets-Sheet 2 Filed Dec. 31, 1962 T- J- CARTER WELL PACKER Jan. 18, 1966 3 Sheets-Sheet 3 Filed Dec. 31, 1962 INVENTOR. 21/0/1405 r]; (here-Q United States Patent 3,229,767 WELL PACKER Thomas J. Carter, San Marino, Calif., assignor to Baker Oil Tools, Inc, Los Angeles, Calif., a corporation of California Filed Dec. 31, 1962, Ser. No. 248,424 12 Claims. (Cl. 166-134) The present invention relates to subsurface well bore apparatus, and more particularly to well packers adapted to be set in well bores for the purpose of performing various functions therein, such as in connection with well production, bridging, cementing, acidizing, or the like.

Well packers have been provided with initially retracted upper and lower slips expanded and held outwardly against the surrounding well casing by upper and lower expanders. An initially retracted packing structure is also expanded against the well casing to prevent fluid leakage past the setting point of the packer in the casing. Heretofore, the initially retracted slips might be expanded prematurely while running the packer in the well casing, as a result of encountering debris, and the like, in the casing, which might act upon a slip, and expander, or other parts of the packer and shift it in a manner to produce slip expansion. In well packers of the type indicated, a substantial setting force might be desired to insure expansion of the slips and packing structure and their firm anchoring in sealing engagement with the wall of the well casing. A large portion of this setting force might be lost during the setting operation in dragging slip elements along the wall of the well casing, resulting in the imposition of an insufiicient setting force on the slips and the packing structure itself.

An object of the present invention is to provide an im proved well packer having slip devices that cannot be expanded inadvertently against the wall of the well casing, and also having expanders that cannot shift inadvertently with respect to the slips, and thereby expand them outwardly of the main body of the packer.

Another object of the invention is to provide a well packer in which the setting force for expanding the normally retracted slip devices and packing structure against the wall of the well casing is substantially entirely available in performing such expanding function, very little of the setting force being expended in sliding parts frictionally along the casing wall.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

FIGURE 1 is a side elevational view of a well packer and a portion of its setting apparatus, the parts being shown in longitudinal section;

FIGS. 2 and 2a together constitute a longitudinal section, on an enlarged scale, through the apparatus shown in FIG. 1 with the parts of the apparatus shown in their initial retracted position for lowering through a well casing, FIG. 2a being a lower continuation of FIG. 2;

FIGS. 3 and 3a are views corresponding to FIGS. 2 and 20 showing certain parts of the well packer in another relative position and with the lower slip structure released and expanded against the well casing, FIG. 3a being a lower continuation of FIG. 3;

3,229,767 Patented Jan. 18, 1966 FIGS. 4 and 4a are enlarged quarter longitudinal sections through the apparatus showing the well packer anchored in packed-off condition in the well casing, FIG. 4a being a lower continuation of FIG. 4.

A well packer apparatus A is illustrated in the drawings, which is adapted to be lowered in a well casing B and anchored in packed-01f condition therewithin against longitudinal movement in both upward and downward directions. The well packer may be lowered in the well casing on a suitable running-in string (not shown), which may be a wire line connected to a setting mechanism C of a known type, such as disclosed in US. Patent No. 2,640,546. The setting mechanism forms no part of the present invention. A portion thereof is shown in the drawings merely for the purpose of disclosing an apparatus for setting the well packer in the well casing.

The well packer A includes a tubular main body 10 having an upper threaded box 11 and a lower threaded pin portion 12 on which a body guide 13 is threadedly mounted. A debris or junk pusher 14, or the like, may be suitably fastened to the lower portion of the guide, as by means of pins 15, this junk pusher having longitudinal slots 16 through which fluid can pass. As is known in the art, the junk pusher 14 has the purpose of pushing debris ahead of the well packer and preventing debris of any significant particle size from passing around the junk pusher 15, possibly wedging the packer in the well casing above its desired setting point.

The wall packer has an upper slip structure or ring 17 for anchoring the packer in the well casing against upward movement, and also a lower slip structure or ring 18 for anchoring the well packer to the casing against downward movement therewithin. The upper slip ring 17 is initially a circumferentially continuous member having upwardly facing wickers or teeth 19 adapted to embed themselves in the wall of the well casing B, the slip structure being slidable relatively along the main body 10 of the packer apparatus. The initial outside diameter of the slip ring 17 is substantially less than the inside diameter of the casing and preferably is no greater than the outside diameter of the junk pusher 14 and of the guide 13, so that any particles that might pass the junk pusher and guide will also travel past the slip ring. The slip ring 17 has an upwardly tapering inner expander surface 20 adapted to coact with a companion external tapered surface 21 on an upper expander or cone 22 slidable with respect to the body 10, but initially releasably secured thereto by one or more shear screws 23 threaded in the expander and received within a circumferential groove 24 in the body.

An upper setting sleeve 25 is disposed around the body 10, its lower head 26 resting upon the upper end of the upper slip ring 17 with the inner tapered surface 20 of the latter engaging the external tapered surface 21 of the expander 22. The setting sleeve 25 is initially held in this position by a shear screw 27 securing it to the main body. As shown, the upper slip ring 17 has circumferentially spaced longitudinal slots 28 extending therethrough partially upwardly from its lower end to provide weakened sections 29 in the slip ring along which it will break into segments upon downward wedging of the slip ring 17 along and over the tapered upper expander 22, as described hereinbelow. Such downward wedging occurs as a result of shifting the setting sleeve 25 downwardly along the body 10 of the tool A.

A packing structure 30 surrounds the body 10 below the upper expander 22. As specifically shown, this packing structure includes a rubber or rubber-like packing element or sleeve 31 having an upper recess 32 in which a circumferentially continuous metallic booster ring 33 is inserted, the upper end of this booster ring engaging the tapered surface 34 of an inner split extrusion preventing ring 35 which has an axial rib 36 received within a companion axial groove 37 in an outer split extrusion preventing ring 38 having a tapered-surface 39 engaging a companion tapered surface 40, on the lower end of the upper expander 22. The rubber packing sleeve 31 has a circumferentially continuous'metallic ring 41 disposed therein slidable along the periphery of the body, this metallic ring having a groove 42 receiving a rubber or rubber-like O-ring 43 for insuring a seal between the packing element and the periphery of the tool body 10, to prevent: fluid leakage therebetween in both longitudinal directions.

The, lower end of the rubber packing element 31 is similar to its upper end, although reversely arranged, and this lower end;coacts with a similar metallic booster ring 33'and.extrusion-preventing rings 35, 38, the outer extrusion preventing ring 38'. ofthe lower set engaging the upper end; ofa lower expander 44 slidably mounted on the; body 1.01ofthe tool andghaving a downwardly tapering externalsurface 45 adaptedto coact with a companion tapered internal surface 46 on the lower slip structure or ring 18,- which is initially circumferentially continuous. The lower slip ring 18 is initially threaded on the body of the tool by providing internal threads 47 on its lower portion threaded onto the externally threaded portion 48 of the lower end of the body on which the guide 13is threaded.- The lower slip ring 18 is threaded on the,body 10 and abuts the upper end of the guide 13. Inadvertentunthreading of the lower slip ring 18 on the body 10 is prevented by tightening the guide 13 against the lower slip ring, the guide functioning as a lock nut and being retained in such tightened position by alock screw 49 threaded therein and into the. body.

The lower expander 44 is prevented from moving upwardly relative to the body by a stop or thrust ring 50, which may be made in two halves or pieces, disposed within a counterbore 51 in the lower expander and engaging an expander shoulder 52 constituting the lower end of the counterbore. The stop or thrust ring 50 also engages a downwardly facing shoulder 53 on the body forming the upper end of a circumferential groove 54 in the body. Relative downward movement of the expander 44 along the body 10 is'prevented initially by one or more shear screws 55 threaded in the expander and received within the body groove 54 between the lower end of the stop ring 50 and the lower side 56 of the groove. The shear screw or screws 55 prevent initial downward movement of the lower expander along the body; whereas, upward movement of the lower expander 44 along the body is prevented by engagement of the expander shoulder 52 with the thrust ring 50, and the engagement of the latter with the downwardly facing body shoulder 53. When the shear screw 55 is intact and disposed in the body groove 54 below the thrust ring 50, there is preferably a gap 58 between the tapered expander surface 45 and the companion tapered internal surface 46 of the lower slip structure 18 (FIG. 2a).

The lower slip structure or ring 18 also has circumferentially spaced longitudinally extending slots 60 therethrough extending partially downwardly from its upper end to provide weakened sections 61 along the slip ring in alignment with these slots at which the ring can break into segments upon wedging of the lower expander 44 thereinto with suflicient force. As shown, the length of the slots 60 in the lower slip ring 18 are substantially greater than the length of the slots 28 in the upper slip ring 17, enabling the lower slip 18 to break into segments and be expandedout against the casing before the upper slip ring 17 can be wedged upon its companion upper expander, 22 and be broken into segments which are expanded outwardly against the wall of the well casing B.

It is also to be noted that a circumferentially continuous ring 62 is-disposedin a recess 63 in the upper end.

of the lower expander 44, the ring being slidable along and engaging the periphery of the-body 10 to prevent downward extrusion of the rubber or rubber-like packing 31 between the body and lower expander 44 upon expansion of the packing element against the wall of the well casing.

The setting sleeve 25 is movable downwardly along the body 10, but is prevented from moving upwardly with respect thereto. A one-way coupling device 65 is provided between the lower head'26 of the setting sleeve and the body. As shown, the body has a longitudinally extending series of peripheral ratchet teeth 66 facing in a downward direction adapted to coact with companion internal ratchet teeth 67facing upwardly in a split latch ring 68 disposed within the head. The exterior of the sleeveis formed as tapered cam teeth 69 adapted to coact with companion internal cam teeth 70 in the head. When the sleeve ratchet teeth 67v are infull mesh with the body ratchet teeth 66, there is a radial clearance between the sleeve cam teeth 69 and the head cam teeth 70 so that the sleeve can expand slightly and ratchet downwardly over the body ratchet teeth 66'. However, any tendency of the setting sleeve 25 to move upwardly of the body 10, or of the body to move downwardly of the sleeve 25, will result in the cam teeth 69, 70 moving axially of one. another and holdingthe ratchet teeth 66, 67 fully in mesh withione. another, thereby'precluding such relative movement.

The upper expander 22 is also prevented from shifting upwardly of the body 10'of the tool, which action could inadvertently shear the screw or screws 23 holding it to the body and effect an undesired wedging of the upper expander within the upper slip ring 17, disrupting the latter and prematurely expanding it against the wall of the well casing. As shown, a one-way split latch ring Silis disposed in an internal circumferential groove 81 in the upper expander below its shear screw, this ring having internal ratchet teeth 82 companion to the ratchet teeth 66' on the body, and also having an outer surface 83 tapering in a downward direction and adapted to coact with a companion internal tapered surface 84 in the expander. When these tapered surfaces 83, 84 are in engagement with theshear screw 23 disposed in the body groove 24, there is an axialdistance 85 between the upper end of the latch or thrust ring 80 and the upper end of the groove 81, such that the upper expander 22 is permitted to shift downwardly of the body 10, following disruption of its shear screw 23, the split ring 80 merely expanding and ratcheting freely downwardly along the body teeth 66.

The well packer parts initially occupy the position illustrated in FIGS. 1, 2 and 2a. The packer is appropriately associated wit-h the setting tool C by means of which it is lowered 'in the well casing B on a wire line (not shown). The setting tool includes a setting sleeve -engaging the upper end of the packer setting sleeve 25 and also a mandrel 91 threadedly attached to a release stud 92, which in turn, is threadedly secured to a head 93 engaging a thrust shoulder or seat 94 on the body guide 13. As described in the above patent, the setting force is provided by a gas under pressure developed in the setting tool C, the setting force being exerted in a downward direction on the setting sleeve 90 of the setting tool and in an upward direction on the mandrel 91, thereby exerting an upward force on the body 10 of the well packer and a downward force on the setting sleeve of the well packer 25.

Prior to generation of the gas under pressure in the setting tool C, the apparatus A, with the setting tool properly connected thereto, is lowered through the fluid in the well casing B to the desired set-ting point. During such lowering action, any foreign matter that might engage the lower slip ring 18-and tend to shift it upwardly along the body ltlrisprevented from doing so by thedirect transmission of the thrust from the slip 18, through the threaded connection 47, 48 to the body of the tool. The lower slip structure 18 is in one piece and circumferentially continuous, so that a substantial force is required to elfect its breaking. In view of the fact that there is initially a slight gap 58 between the slip 18 and the expander 44, there is no tendency for the slip to be wedged upwardly along the lower expander and be broken into segments which would be shifted outwardly against the wall of the well casing.

During downward movement of the well packer A in the well casing B, any foreign material that might tend to shift the lower expander 44 upwardly cannot do so since such upward thrust is transmitted directly from the expander shoulder 52 through the stop or thrust ring 50 to the body shoulder 53. Substantially none of the thrust is imposed upon the shear screw 55 initially releasably attaching the lower expander 44 to the packer body 10.

Moreover, during downward movement of the well packer through the fluid in the well casing, debris or other material that might engage the upper expander 22 cannot disrupt its shear screws 23 and shift it upwardly Within the upper slip ring 17, since such thrust is transmitted from the upper expander to the split coupling ring 80, and through its ratchet teeth 82 to the body ratchet teeth 66, and to the body 10 itself. Thus, the shear screw or screws 23 do not have any of such load imposed upon them and they will remain intact, holding the upper expander 22 against longitudinal movement in both an upwardly and downwardly direction along the main body 10 of the well packer.

Finally, any foreign material that might engage the upper slip ring 17 cannot shift it upwardly since such upward movement is transmitted directly to the setting sleeve 25 and through the latch ring 68 to the body 10 of the tool. As shown in FIG. 2, the upper end 96 of the latch ring engages a downwardly facing shoulder 97 on the body 10 of the tool. Such upward force, if imposed on the setting sleeve 25, cannot shear its screw 27 since the upward force is transmitted through the latch ring 68 to the body of the well packer.

When the location in the well casing is reached at which the well packer A is to be set, the setting tool C is actuated and fluid under an increasing pressure generated therein. As stated above, such fluid pressure will exert a downward force on the setting sleeve 90 and an upward force on the mandrel 91. The downward force on the packer setting sleeve 25 will first disrupt the shear screw 27 attaching it to the body 10, this setting sleeve and its ratchet sleeve 68 moving downwardly, shifting the upper slip ring 17 downwardly of the body. The tapered surface 20 of the slip ring 17 preferably initially snugly engages the external tapered surface 21 of the upper expander 22, so that the downward force is promptly transmitted to the latter. The shear screw 23 securing the expander 22 to the body of the tool has a much lesser shear strength than the force required to break the upper slip ring 17 into segments at the regions 29 above its slots 28. Accordingly, the upper slip ring 17 and upper expander 22 shift downwardly as a unit, after the shear screw or screws 23 have been sheared from the body 10 of the tool, these parts moving downwardly and carrying the split thrust ring 86 downwardly along the body, which will merely ratchet along its teeth 66, the entire packing structure 30 being urged downwardly of the body, although the packing sleeve 31 itself might bulge outwardly slightly, depending on its degree of hardness.

The downward force is transmitted through the lower expander 44, its shear screw or screws 55 engaging the lower body shoulder 56 and being sheared at the body 10, releasing the lower expander 44 from the body and causing it to shift downwardly within the lower slip ring 18. As the downward setting force increases, the setting sleeve 25, upper slip ring 17, upper expander 22, packing structure 30, and lower expander 44 move downwardly as a unit, the lower expander overcoming the strength of the lower slip ring 18 at its weakened sections 61 and breaking such slip ring into segments. Upon their breaking, the segments are freed from the body and are capable of being expanded outwardly, sliding along the upper end of the guide 13, with the internal thread 47 being freed from the external body thread 48. The lower expander 44 will shift downwardly within the lower slip segments until the latter are embedded in the wall of the well casing B, as illustrated in FIGS. 3 and 3a.

Downward shifting of the setting sleeve 25 along the body 10 continues, the upper slip ring 17 having much greater resistance to breaking than the lower slip ring 18 and remaining intact. The upper slip ring 17 and expander 22 then shift downwardly toward the lower expander 44, which cannot move downwardly to any further extent because of the anchoring of the lower slip segments 18 in the wall of the well casing. As a result, the packing structure 30 is shortened between the upper and lower expanders and is expanded outwardly against the wall of the well casing. The extrusion preventing devices 35, 38 are also expanded outwardly against the wall of the well casing, or at least partially expanded toward the wall of the well casing. As the setting force on the sleeve 25 continues to increase, to more firmly embed the lower slip 18 in the wall of the well casing and to expand the packing structure 30 against the casing wall, the strength of the upper slip ring 17 at its weakened sections 29 is finally exceeded, and the latter then breaks into segments along such weakened sections and is shifted downwardly along the upper expander 22 and outwardly into engagement with the wall of the well casingv Following such outward engagement, the downward setting force on the sleeve 25 and the upward force on the body 10 exerted through the mandrel 91 continues to increase, further shortening the packing structure 30 and insuring its firm sealing engagement against the wall of the well casing B and also against the periphery of the body 10. However, the further outward expansion of the packing structure against the well casing and the further wedging of the upper slip segments against the wall of the well casing occur with only a relatively short downward sliding of the upper slip segments 17 along the wall of the well casing, since the slip segments 17 are not expanded until there has been a large extent of expansion of the packing structure 30 against the wall of the well casing.

The setting force continues to increase as a result of an increase in gas pressure in the setting tool C until the strength of the release stud 92 is exceeded, whereupon such release stud is pulled apart at its weakened section 9201 to free the mandrel 91 from the head 93, the latter dropping harmlessly downwardly through the junk pusher 14 into the well bore. The setting tool C, including its mandrel 91 and setting sleeve 90, can now be elevated in the well casing B and removed at the top of the hole.

The well packer will remain in its set condition. The one-way ratchet sleeve device 65 prevents return or upward movement of the packer setting sleeve 25 with respect to the body 10 and holds the parts anchored in packed-01f condition in the position shown in FIGS. 4 and 4a. The extrusion preventing devices 35, 38 prevent cold flow or extrusion of the rubber packing element 31 through the clearance space between the upper expander 22 and easing B and through the clearance space between the lower expander 44 and casing. The extrusion preventing ring 62 will bridge any clearance space between the lower expander 44 and the periphery of the body 10, preventing the packing material from flowing through such clearance space.

The split thrust ring prevents inadvertent shearing of the screw 23 holding the upper expander 22 to the body 10 during lowering of the apparatus in the well casing, and consequent upward shifting of the upper expander along the body of the tool. The location of such ring 80 in the upper expander protects it and also insures against its interference with any of the other parts of the apparatus. Moreover, its location below the groove 24 receiving the shear screw 23, and initially securing theupper expander to the body, insures against its inadvertent shifting into such groove, which might preclude proper operation of the apparatus, as, for example, in the event of its having been placed in the upper expander above the body. groove 24.

As described above, the well packer is set by first disrupting the lower slip ring 18 and expandingit outwardly. As a result, a substantial expansion of the packing structure 30 against the Well casing is obtained before the upper slip ring 17 is disrupted and expanded against the well casing, minimizing the extent of sliding of the upper slip ring segments along the wall of the well casing. Such sliding action would have resulted in a substantial portion of the setting force being consumed in overcoming the friction of the upper slip ring segments against the wall of the well casing, and a corresponding lesser amount of such setting force would. have been available for anchoring the slips 17, 18 in the well casing and firmly expanding the packing structure 30 against the casing wall, as well as against theperiphery of the body. In lieu of. first setting the lower slip structure 18, the well packer is to be set in the well casing by first disrupting the upper slip ring 17 and expanding it against the well casing, following by expansion of the packing structure 30 against. the casing, and expansion of the lower slips 18 against the casing, the upper slip ring 17 would be weakened to a substantially. greater extent than the lower slip ring, as by providingmuch longer circumferentially spaced slots 28 through the upper slip ring. and shorter circumferentially spaced slots 60in the lower slip ring 18. In both cases, sliding of the slip structure last expanded against the casing is considerably reduced, thereby decreasing the lost setting force incident to sliding of the slips along the casing wall, and insuring the presence of a greater effective setting force inexpanding the packing structure 30 against the casing wall C and against the packerbody 10.

I claim:

1. In well apparatus adapted to be disposed in. awell bore: a body; a circumferentially continuous annular slip member threaded on said body and having one or more weakened regions .at which said slip member can break; means for preventing rotation of said slip member on said body; an expander mounted on said body; and means for relatively forcing said expander against said slip member to break said slip member at its one or more weakened regions and expand said slip member laterally outwardly.

2. In well apparatus adapted to be disposed in a well bore: a body; a circumferentially continuous annular slip member threaded on said body and having circumferentially spaced weakened regions at which said slip member can break. into slip segments; means for preventing rotation of said slip member on said body; an expander mounted on said body; and means for relatively forcing said expander against said slip member to break said member into said segments and expand said segments laterally outwardly.

3. In well apparatus adapted to be disposed in a well bore: a body; a circumferentially continuous annular slip member threaded on said body and having circumferentially spaced slots providing weakened regions at which said slip member can break into slip segments; an expander mounted on said body above said slip member; and means for relatively forcing said expander downwardly against said slip member to break said member into said segments and expand said segments laterally outwardly.

4. In well apparatus adaped to be disposed in a well bore: a body; a circumferentially continuous annular slip member theraded on said body and having one or more weakened regions at whichsaid slip member can break;

an expander mounted on said body; means for relatively forcing said expander against said slip member to break said slip member at its one or more weakened regions and expand said slip member laterally outwardly; and means threaded on said body and bearing against said slip member to lock said slip member to said body.

5. In well apparatus adapted to be disposed in a well bore: a body; a circumferentially continuous annular slip member threaded on said body and having circumferentially spaced slots providing weakened regions at which said slip member can break into slip segments; an expander mounted on said body; means for relatively forcing said expander against said slip member to break said member into said segments and expand said segments laterally outwardly; and means threaded on said body and bearing against said slip member to lock said slip member to said body.

6. In well apparatus adapted to be disposed in a well bore: a body having a downwardly facing shoulder; slip means on said body; an expander mounted on said body above said slip means and having an upwardly facing shoulder below said body shoulders; frangible means initially securing said expander to said body; a thrust ring between and engageable with said shoulders to transmit upwardly directed forces on said expander to said body and to prevent transmission of upward forces on said expander through said frangible means to said body, said expander surrounding said thrust ring to prevent its lateral outward movement from engagement with said body shoulder, and means for moving said expander relatively downwardly on said body to disrupt said frangible means and for then forcing said. expander relatively downwardly against said slip means to expand said slip means laterally outwardly.

7. In well apparatus adapted to be disposed in a well bore: a body; normally retracted slip means on said body; an expander mounted on said body below said slip means; frangible means initially securing said expander to said body; means above and engaging said slip means and movable downwardly of said body to shift said slip means downwardly along said expander and laterally outwardly; one-way lock means between said shifting means and body permitting downward movement of said shifting means along said body while preventing upward movement of said shifting means along said body; and one-way latch means within said expander below said frangible means engageable with said body prior to movement of said slip means downwardly along said expander to prevent relative upward movement of said expander on said body while permitting relative downward movement of said expander on said body.

8. In well apparatus adapted to be disposed in a well bore: a body having ratchet teeth disposed along its length; normally retracted slip means on said body; an expander mounted on said body below said slip means; frangible means initially securing said expander to said body; means above and engaging said slip means and movable downwardly of said body to shift said slip means downwardly along said expander and laterally outward-1y; one-way lock means carried by said shifting means and having ratchet teeth engageable with said body teeth to permit downward movement of said shifting means along said body while preventing upward movement of said shifting means along said body; and one way latch means within said expander below said frangible means and engageable withsaid body teeth prior to movement of said slip means downwardly along said expander to prevent relative upward movement of said expander on said body while permitting relative downward movement of said expander on said body.

9. In well apparatus adapted to be lowered and set in a well bore: a body; upper and lower circumferentially continuous annular slip members on said body; each slip member-having one or more weakened regions atwhich it can break, the one or more weakened regions of one slip member having substantially lesser strength than the one or more weakened regions of said other slip member; upper and lower expanders on said body coacting with said upper and lower slip members, respectively; and means for relatively forcing said expanders against their respective slip members to break said slip members at said one or more weakened regions and expand them laterally outwardly.

10. In well apparatus adapted to be lowered and set in a well bore: a body; upper and lower circumferentially continuous annular slip members on said body; each slip member having circumferentially spaced slots providing weakened regions at which the slip member can break, the slots of one slip member being substantially longer than the slots of another slip member so that the weakened regions of said one slip member have substantially lesser strength than the weakened regions of the other slip member; upper and lower expanders on said body coacting with said upper and lower slip members, respectively; and means for relatively forcing said expanders against their respective slip members to break said slip members at said weakened regions and expand them laterally outwardly.

11. In well packer apparatus adapted to be lowered in and set in a well bore: a body having external threads thereon; a lower circumferentially continuous annular slip member having internal threads threaded on said external threads and also having weakened regions at which said slip member can break; a lower expander on said body above and adapted to coact with said lower slip member; a packing structure on said body above and engageable with said lower expander; an upper expander on said body engaging the upper end of said packing structure; an upper circumferentially continuous annular slip member engageable with said upper expander and having weakened regions at which said upper slip member can break; and means for shifting said slip members toward each other to expand said packing structure and to force said slip members against their respective expanders, whereby said slip members are disrupted at their weakened regions and expanded laterally outwardly.

12. In well packer apparatus adapted to be lowered and set in a well bore: a body having ratchet teeth disposed along its length and also having lower external threads; a circumferentially continuous lower annular slip member threaded on said body threads and having circumferentially spaced slots providing weakened regions at which said slip member can break; a lower expander on said body engageable with said lower slip member; an initially retracted packing structure on said body having its lower end abutting said lower expander; an upper expander on said body engaging the upper end of said packing structure; an upper circumferentially continuous annular slip member on said body engageable with said upper expander and having circumferentially spaced slots providing weakened regions at which said upper slip member can break; said upper member slots being substantially shorter in longitudinal extent than said lower member slots; means engaging said upper slip member and movable downwardly along said body to expand said packing structure laterally outwardly and to disrupt said slip members at their weakened regions and cause said expanders to expand said slip members laterally outwardly; one-way lock means on said shifting means having ratchet teeth engaging said body ratchet teeth to permit downward movement of said shifting means along said body but preventing upward movement of said shifting means along said body; one-way latch means within said upper expander having ratchet teeth engaging said body ratchet teeth to prevent upward movement of said upper expander along said body while permitting downward movement of said upper expander along said body; said lower expander having an upwardly facing shoulder, said body having a downwardly facing shoulder; and a thrust ring between and engaging said shuolders to prevent upward movement of said lower expander along said body.

References Cited by the Examiner UNITED STATES PATENTS 1,092,540 4/1914 Robinson 166135 1,853,474 4/1932 Tucker 166135 2,121,002 6/1938 Baker 166-134 2,368,409 1/1945 Burt 166-134 2,589,506 11/1952 Morrisett 166--134 2,737,242 3/1956 Baker 1'66134 3,002,564 10/1961 Baker 166134 3,062,292 11/1962 Lowrey et al. 166-123 3,082,824 3/ 1963 Taylor et al. 166-123 CHARLES E. OCONNELL, Primary Examiner.

BENJAMIN HERSH, Examiner. 

1. IN WELL APPARATUS ADAPTED TO BE DISPOSED IN A WELL BORE: A BODY; A CIRCUMFERENTIALLY CONTINUOUS ANNULAR SLIP MEMBER THREADED ON SAID BODY AND HAVING ONE OR MORE WEAKENED REGIONS AT WHICH SAID SLIP MEMBER CAN BREAK; MEANS FOR PREVENTING ROTATION OF SAID SLIP MEMBER ON SAID BODY; AN EXPANDER MOUNTED ON SAID BODY; AND MEANS FOR RELATIVELY FORCING SAID EXPANDER AGAINST SAID SLIP MEMBER TO BREAK SAID SLIP MEMBER AT ITS ONE OR MORE WEAKENED REGIONS AND EXPAND SAID SLIP MEMBER LATERALLY OUTWARDLY. 